The UW STAART Center will address the following overall objectives: (1) To determine social, linguistic, neuropsychological, and electrophysiological characteristics that distinguish very young children with autism from children with developmental delay and those with typical development. Such research will enhance our ability to recognize autism early in life so that children with autism can be helped as early as possible, and their long-term outcome can be improved (Projects I and II). (2) To assess the efficacy of early intensive behavioral intervention for improving outcomes for children with autism, and to determine whether child neurocognitive factors moderate the effects of early intervention. Such knowledge will inform decisions regarding individualized interventions, elucidate brain mechanisms, and shed light on questions related to brain plasticity (Project I). (3) To increase our understanding of the neurobiological bases of autism by studying abnormalities in brain structure (via magnetic resonance imaging) and brain chemistry (via magnetic resonance spectroscopy) in very young children with autism, as compared to children with developmental delay and those with typical development (Project III). (4) To enhance our understanding of the cognitive neuroscience of autism by studying core social cognition impairments in high-functioning individuals with autism using event related brain potentials and functional magnetic resonance imaging. This information is relevant for early identification, development of more refined interventions, and measurement of quantitative genetic traits (Project IV). (5) To conduct molecular biology studies aimed at gene discovery in autism. Identification of susceptibility genes in autism is important for early identification, prevention, and medical treatment (Project V).